Question

Atmosphere maintain the temperature on the surface of earth because
A. It contains water vapour in it.
B. It holds air, which is a bad conductor of heat.
C. It reflects the heat rays.
D. It absorbs the heat rays.

Answer 1

Hint: Energy is transferred between the earth's surface and the atmosphere in different ways, including conduction, convection, and radiation. Conduction, convection, and radiation all have a function in transferring heat from earth's surface to the atmosphere.

Complete step by step solution:
The heat energy from the Earth's surface is transferred to the atmosphere by the process of conduction. Contact of the atmosphere with the warm surfaces on the earth transfers thermal heat energy, which then heats up the rest of the air through convection (It is a mode of heat transfer by the motion of a fluid like air. Heat transfer by convection occurs to the surface of an object where the surrounding molecule or atom is heated and passed energy away from the source of heat). Heat transfer also takes place through radiation (It is a mode of heat transfer by radiation, in this heat is transferred by electromagnetic waves. It is different from conduction and convection as it does not require any medium for transferring heat energy) but not as significant as conduction and convection.
As we know that the heat is conducted by molecules or atoms that are very closely bonded together and vibrating at high frequency. But since air molecules are scattered at a much larger distance, it is termed as a bad conductor of heat. This is because to conduct heat molecules should absorb heat and transmit it to the nearby molecule by vibrating, but the nearby molecule is so far that this vibration should be very high. So, the heat energy required is high for conduction to start.
Atmosphere maintains the temperature on the surface of earth because it holds air which is a bad conductor of heat because its molecules are not in continuous touch with one another. Air molecules are too far to conduct heat to another molecule efficiently. Since air is a poor conductor of heat, most heat energy transfer by conduction takes place right near the surface of the earth.

Note:
Half of the solar radiation that hits the top of the atmosphere is filtered out before it touches the ground. This energy is absorbed by atmospheric gases, reflected or scattered by clouds or some particles. Some of the energy that hits the ground is reflected back into the atmosphere. The rest is absorbed by the earth's surface.